Safety is of paramount importance to line crew operators who deal with high voltage electrical equipment given the consequences of a mistake or an unfortunate occurrence. High voltage electrical equipment includes, but is not limited to, various sized bushing inserts, feed-through devices, multi-position junctions, and insulated or stand-off bushings. The foregoing equipment is usually held in a fixed position to receive mounting connectors such as appropriately sized elbow connectors, insulating caps and the like. Although interconnection between a particular type of accessory product and a connector is discussed herein, it will be appreciated that the existing problems and the solution is applicable to all accessory products and their connections.
One of the more dangerous tasks performed by an operator is disconnecting a live source of power by physically breaking a connection between the foregoing rather than throwing a switch. A risk in performing such a disconnect is that the electricity from the live end of the connection may arc or flashover to ground. Such a flashover can damage the equipment and may cause injury. For example, one such a flashover problem has been found to occur when elbow connectors are removed from bushing inserts.
A typical prior art bushing insert and elbow connector are depicted in FIGS. 1 and 2. The bushing insert is indicated generally by the numeral 10 while the cable or elbow connector is indicated generally by the numeral 12. Bushing insert 10 includes a body with semi-conductive shielded collar 14 that is substantially cylindrical but may be slightly tapered. A semi-conductive shielded sheath 16 extends from one end of collar 14. Sheath 16 and collar 14 provide protection and a ground shield for bushing insert 10. The body also includes a non-conductive frusto-conical portion 18 or first portion extends outwardly from the other end of collar 14 and terminates at an annular locking groove 20. A snuffer assembly 21 extends from frusto-conical portion 18. Snuffer assembly 21 is provided to protect the internal components of bushing insert 10. A shoulder wall or portion 22 forms the connection between collar 14 and frusto-conical portion 18. Shoulder wall 22 is disposed at a substantial right angle with respect to collar 14 and joins frusto-conical portion 18 in a small chamfer. Bushing insert 10 provides an inner bore with an internal electrical connection components or conductive component therethrough to provide a medium for electrically connecting elbow connector 12 to other electrical distribution equipment. A second portion extends from collar 14 for connection to an equipment bushing well.
Elbow connector 12 includes a bushing port 24 having an interior wall 26 that is configured to tightly conform to frusto-conical portion 18 of bushing insert 10. Bushing port 24 is thus configured to snugly engage bushing insert 10 when elbow connector 12 is locked on bushing insert 10. This position is depicted in FIG. 1. When elbow connector 12 is locked on bushing 10, a lip 28 of bushing port 24 is positioned over a portion of collar 14. Lip 28 includes a terminal wall or end 30 and an inner wall 32. Lip 28 joins with the body of bushing port 24 forming a shoulder 34 having an end wall 36. End wall 36 contacts shoulder wall 22 and inner wall 32 contacts collar 14 when elbow connector 12 is locked on bushing insert 10. Furthermore, interior wall 26 of elbow connector 12 snugly engages frusto-conical portion 18 of bushing insert 10 when elbow connector 12 is locked on bushing insert 10. Connecting elbow connector 12 to bushing insert 10 is enhanced by the presence of a high dielectric lubricant that may be used to provide a well lubricated fitting between bushing insert 10 and connector 12. An electrical probe 37, which is connected to an electrical cable, is concentrically disposed within bushing port 24 and extends into the electrical connection components within bushing insert 10.
The problem encountered with the connection between bushing insert 10 and connector 12 in the prior art is depicted in FIG. 2. FIG. 2 shows a position of connector 12 as it is removed from bushing insert 10. In this position, bushing port 24 and lip 28 have moved slightly off of bushing insert 10 forming gaps 38 between end wall 36 and shoulder wall 22 as well as between frusto-conical portion 18 and interior wall 26. Gaps 38 form vacuums or partial vacuums given the tight connection between lip 28 and collar 14 as well as between bushing port 24 and frusto-conical portion 18. Testing has revealed that an especially large vacuum occurs between end wall 36 and shoulder wall 22 as connector 12 is removed from bushing insert 10. The existence of lubricant on these elements also aids the formation of a vacuum in gaps 38. The existence of a vacuum or partial vacuum in gaps 38 increases the likelihood of a flash-over between electrical probe 37 and the shielded collar 14 over the insulated frusto-conical portion 18. This flashover or electrical arc will damage bushing insert 10 and connector 12, requiring their replacement.
It is thus desired in the art to provide a device that prevents the vacuums from forming between bushing insert 10 and connector 12 while connector 12 is removed from bushing insert 10. Such a device ideally would be able to be retrofit onto existing bushing inserts such that the entire bushing insert would not have to be replaced to provide this benefit. Furthermore, the desired device could be easily manufactured to fit a wide variety of rated bushing inserts, junctions and other similar accessory products.
Another safety problem with bushing inserts and connectors is that the operator installing the connector on the insert does not always know when the connector is fully attached to and locked on the bushing insert. Although an experienced operator may develop a feel for a secure and locked connection between the two elements, the inexperienced operator who infrequently connects the items desires an indicator that tells them when the two elements are fully locked together. It is thus desired in the art to provide a device that gives an indication to the operator of when the connector is fully installed on the bushing insert. Such a device should ideally be able to be manufactured to fit a wide variety of bushing insert sizes and accessory products and be capable of being retrofit onto existing bushing inserts.